CHAP. 2. 20. CAUSE OF THE HALO. &c. 105 



ill a cloud before llain, has been alluded to by 

 Aristotle,* Virgil,f and others. 



RABDVS PYRAMIDALIS. Portio pyramidalis 

 lucis in nube visa, quasi ex Sole procedens, 

 cujus vertex diametro Soils horizontali per- 

 pendicularis est. 



Not uncommon in haze of a peculiar kind, 

 perhaps cirrostratus. Sometimes small portions 

 of the Rainbow's colours appear in different 

 places. I observed this between seven and 

 eight o'clock, 21st August, 1812, while riding 

 between Ticehurst and Wadhurst, in the 

 neighbourhood of Tunbridge Wells ; and a 

 similar phenomenon is recorded as seen at 

 Walthamstow, March 24, 17854 



SECTION XX. 



Of the causes of the abovedescribed Phaenomena. 



IN examining what may be the causes of the 

 various phaenemena above described, I make a 



* Arist. Meteor, lib. iii. cap. 2. 

 t Virgil Georg. lib. i. v. 445. 



% Noted in a Journal kept by E. Forster, Esq. from Jan. 

 1785 to April 1812 inclusive. 



